"The case is the latest in a growing controversy nationwide over the use of lethal injection for executions. Sources for the necessary drugs have dried up, and states with death penalties are scrambling to find more.

"Convicted killer Clayton Lockett was slated to be executed Thursday by lethal injection and a second Oklahoma inmate, Charles Warner, was to die March 27. Lockett's execution was postponed until April 22 and Warner's to April 29.

"Lockett is awaiting execution for his role in the shooting death of a 19-yer-old woman in 1999. Warren is on death row for murdering his girlfriend's 11-month-old daughter in 1997."

As NBC News reports, the issue has been that some manufacturers have refused to sell chemicals to correction officials wanting to use them for executions. That has forced some states "to come up with new cocktails or turn to less-regulated compounding pharmacies."

NBC News adds:

"Both routes have hit snags.

"In Ohio, for instance, the first prisoner executed with the readily available drugs midazolam and hydromorphone took 25 minutes to die and was described as gasping for breath."